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A group of international scientists, including a team from the University of Southampton, have today published their research arguing that current assessments of climate change risks need to take into account what is already being experienced rather than rely only on modelled predictions.

Most current climate models take a “top down” approach by projecting changes such as rising sea levels and changing rainfall patterns, then use these projections to inform strategies that local communities in vulnerable regions can use to adapt. By contrast the researchers have carried out a “bottom up” approach which studies how communities in the regions most at risk have responded to past and present changing conditions and believe that a combination of both approaches is needed to create the most sustainable adaption strategies.

The research team was led by Decclan Conway of Grantham Research Institute at LSE and the team included Professor Rob Nicholls and Dr Sally Brown of the University of Southampton.

As part of their research, published today in the scientific journal Nature Climate Change, the researchers evaluated four case studies by the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA) project in three climate-sensitive ‘hotspots’. These are river deltas, semi-arid lands, and river basins dependent on glaciers and melting snow – areas with high numbers of vulnerable, poor or marginalised people and a strong risk of significant climate change impacts.

The top down approach showed that these regions will be affected by higher than average rising changes and notable difference in rainfall. However this model could not predict how the communities there would respond to these changes – such as through migration, business decisions and livelihood choices – with a high degree of certainty. The researchers were able to produce a much more informed assessment of the specific sensitivities to climate in the regions risks by studying CARIAA’s engagement with the communities on the ground and understanding how they are already adapting to change.

The studies carried out across deltas (including the Ganges-Brahmaputra, Indian Mahanadi and African Volta) indicate that socially marginalised populations have a very limited range of adaptation options open to them, and that established migration flows, which are one way people act to avoid or limit climate risk, are themselves sensitive to climatic changes. Being mobile – to commute to carry out work or to relocate to a location with lesser risks – was also shown to be an essential feature of many livelihoods (such as pastoralism, farming and natural-resource-based trading) in the semi-arid study regions within Ghana, Kenya, Namibia and India.

Rob Nicholls, Professor of Coastal Engineering at the University of Southampton said: “as our research shows, measuring the direct effect of climate change is challenging as everybody experiences climate change in different ways. We need these new methods to better understand how climate change affects different sectors of society”.

Dr Sally Brown, senior research fellow at the University of Southampton and Bournemouth University said: “Combining these high level assessments and community focused methods provides much richer information. This can help target actions to identify the real adaptation needs given climate change.”

Overall, the bottom-up studies provide valuable insights into vulnerabilities within societies that have already experienced climate change impacts locally. Top-down and bottom-up approaches provide complementary insights into who and what is at risk so integrating their results is a much needed step towards addressing their immediate adaptation requirements.